Heat Flux and Pressure Profiles in an Oxygen/Hydrogen Multielement Rocket Combustor

Proof of the predictive accuracy of models used in simulation of the high-pressure, high-heat flux environments inside operating rocket combustion chambers is limited by several factors including multiple phases, unsteadiness, high energy release, turbulence, and complex flow geometry. The severe environment also complicates the measurement of temperature, pressure, and chemical composition within the combustor. This paper describes an experiment to collect and analyze benchmark-quality validation data for a multi-element rocket combustor using liquid oxygen and gaseous hydrogen operating at chamber pressures from 300 to 1000 psia at mixture ratios from three to six. For these propellants, the stoichiometric mixture ratio is eight. The combustor was instrumented with 44 coaxial thermocouple pairs to measure axial and circumferential temperature fields and 8 pressure transducers to measure axial pressure profiles. The local heat flux at the inner wall of the combustion chamber computed at each temperature measurement location was found to vary between 4 and 20 Btu/in. 2 /s. The circumferential variation of heat flux seems to indicate mixing and radial outflow of combustion gases between injector elements, a phenomenon that is not observed in injector configurations with tighter spacing. Further, the axial pressure profiles and head-end temperature measurements suggest the presence of recirculation zones near the injector face.